During the past decades, enormous efforts have been dedicated to the establishment and culturing of plant-based systems for the accumulation and harvesting of native or heterologous proteins and secondary metabolites. The literature provides a vast quantity of evidential material that proves the utility of plant-based systems to produce a large variety of desired substances that are either secreted into the culture medium or isolated from the producing cells, tissues, organelles or even whole plants or parts thereof. Likewise, a broad range of transformation protocols exist that ensure the establishment of either stably or transiently transformed plant material. However, there is still a need for a reliable, relatively cost-efficient and rapid technology to obtain high yields of a desired product from plant cells.